Just sent mine back for some of the same issues. It has done it several times now, even after doing all the calibrations and having plenty of sats. Some times it flys like a dream and then all of the sudden it goes crazy and cant seem to stabilize itself. Had the bounce landing (this has happened 3 time now) with the unstable flight and decided to call Yuneec Support after replacing my 5th prop... Supposed to arrive in Cali on Monday. Let me know what your outcome is.
Just bought a yuneec typhoon h also having these same issues! Tried two times, having it hover 3-10 feet off the ground for 2 minutes, and it starts toilet bowling, then all **** breaks loose like it wants to fly away but in larger circles, luckily i managed to get it on the ground!
If youve done all the calibrations correctly and its still doing it then only thing to do is call support. They will have you send it back to fix. I finally got a new one in replacement after a couple trips to support and it has been flawless.